[sengli]

My Gen5 did this same scenario to me too. Where for no reason it was just stone cold dead one day. Eventually had the dealer replace the battery under warranty, which made sense. Anyway I also leave mine on a battery tender when not in use. Beware though...a couple of years ago a bad thunder storm rolled through. Had a close lightning strike, and it blew up my tender while attached to the car. It blew up the BCM, and anti-lock module and two sensors on my C6 Z06. Cost pretty close to $3k to get it fixed, thankfully with insurance. If I even think there is chance of a storm now...I unplug it.